The Diablo III Website announces that a pretty basic feature is soon being added to Battle.net; the ability to appear offline. This will actually be patched into each game individually, starting with the upcoming version 1.0.5 patch for Diablo III:

In the coming months, we're planning an update to Battle.net that will give you more control over your online presence when playing Blizzard games. Soon, World of Warcraft, StarCraft II, and Diablo III players will be able to select "Appear Offline" as one of their Battle.net social-status options (along with Available, Busy, and Away) for those times when they want to wander Azeroth by their lonesome, dominate the galaxy in radio silence, or slay demons in solitude. When you choose this option as your status, all of your Real ID friends, BattleTag friends, and character-level friends will see you as “Offline” in their friends list whenever you’re logged into a game.

The “Appear Offline” status option will be added to World of Warcraft, StarCraft II, and Diablo III separately in future updates for each game. For Diablo III, we expect to add the feature in a patch after 1.0.5. For World of Warcraft and StarCraft II, we expect to add the option sometime after the release of each game’s upcoming expansion.

Alamar wrote on Sep 21, 2012, 08:51:This has half worked on Steam for ages...

Just the other (work) day, I went offline in my steam friends list, and they couldn't see me playing Borderlands 2... Too bad my boss saw the achievements I got : )

-Alamar

The trouble is that going "offline" in friends disables all community related functionality (MP basically) in several Steamworks games. What he wants is an Appear Offline toggle that doesn't also disable any functionality.

Bhruic wrote on Sep 20, 2012, 21:22:The sad thing is that as slow as they were to implement this, and as minor a feature it is, they are still adding this functionality before Steam is. Seriously Valve, how hard would it be to put this in place?

This has half worked on Steam for ages...

Just the other (work) day, I went offline in my steam friends list, and they couldn't see me playing Borderlands 2... Too bad my boss saw the achievements I got : )

El Pit wrote on Sep 21, 2012, 00:39:WHAT?! But you can be logged in to Steam AND "appear offline" since the first life forms left the sea. What are you talking about?

No, you can be logged into Steam and be offline. You can't appear offline. Appearing offline allows you to continue to monitor your friends list, communicate while "offline" with a specific person if you choose to, etc. Steam does none of those things. If you choose "offline", that's what happens, you go offline. No viewing your friends list, and definitely no communications with anyone.

El Pit wrote on Sep 21, 2012, 00:39:WHAT?! But you can be logged in to Steam AND "appear offline" since the first life forms left the sea. What are you talking about?

No, you can be logged into Steam and be offline. You can't appear offline. Appearing offline allows you to continue to monitor your friends list, communicate while "offline" with a specific person if you choose to, etc. Steam does none of those things. If you choose "offline", that's what happens, you go offline. No viewing your friends list, and definitely no communications with anyone.

The reason I stopped playing Starcraft II was because of this. People would get on and start talking to me while I was playing a game and I could not respond to them while the game was paused. the game had to be in motion to be able to chat for some reason. It was utter bullshit.

Bhruic wrote on Sep 20, 2012, 21:22:The sad thing is that as slow as they were to implement this, and as minor a feature it is, they are still adding this functionality before Steam is. Seriously Valve, how hard would it be to put this in place?

WHAT?! But you can be logged in to Steam AND "appear offline" since the first life forms left the sea. What are you talking about?

The sad thing is that as slow as they were to implement this, and as minor a feature it is, they are still adding this functionality before Steam is. Seriously Valve, how hard would it be to put this in place?

Verno wrote on Sep 20, 2012, 15:22:I think you're being optimistic, I totally expect Blizzard to embrace the console in a big way at some point. Millions of sales and your fans will tolerate pretty much any abuse, publishers wet dream. I'm assuming the only thing holding that back is battle.net.